8/8/2019 3.1 Chemical Elements and Water WORD

1/2

Essential Biology 03.1: Chemical Elements and Water

1. What are the four most commonly occurring elements in living things?

Carbon, Hydrogen, Oxygen and Nitrogen are the four most commonly occurring

elements in living things.

2. State some functions of each of these elements in living things:

a. Iron Symbol: Fe Ion:

Function(s): oxygen binding component of haemolobin (animals) and isused to make chlorophyll and used in photosynthesis (plants)

a. Sulphur Symbol: S Ion: 4H2S (hydrogen sulphide)

Function(s): found in amino acids, reactant for chemosynthetic bacteria

b. Calcium Symbol: Ca Ion: CaCO2(calcium carbonate)

Function(s): synaptic transmission, muscle contraction, structure of bonesand teeth and blood clotting

c. Phosphorous Symbol: P Ion:

Function(s): phospholipid bilayer formation and active component in ATPmolecules, make up part of backbone of DNA

d. Sodium Symbol: Na Ion: NaCl (sodium chloride)

Function(s): action potential for nerve impulse and is main cotion in bloodplasma

e. Potassium Symbol: K Ion:

Function(s): nerve impulses and has a strong influence in osmosis, maincotion in cell cytoplasm.

3. In the space below, draw three water molecules attracted to one anotherby hydrogen bonding. Include labels to show the polarity of the molecules.Annotate: How does H-bonding work?

Stephen Taylor Bandung International Schoolhttp://sciencevideos.wordpress.com

http://sciencevideos.wordpress.com/http://sciencevideos.wordpress.com/

8/8/2019 3.1 Chemical Elements and Water WORD

2/2

Essential Biology 03.1: Chemical Elements and Water

6. Water has many properties which are essential for life. Complete the table below.

Explanation Significance to living things

Thermal Properties

Water has a high specific heat capacitywhich means that it takes a lot ofenergy for the temperature to changedue to the many h-bonds which in turncauses the temperature to remain

generally stable.

Most organisms have a narrow rangeof conditions that they can live in, theslow temperature changes aresuitable for these organisms as thereis no extreme change in a shortperiod of time. Water is also a good

coolant, it heats slower than air orland which is good for animals inwarmer climates and the evaporationof water also removes a lot of heat.This helps avoid damaged tissues anddenature proteins that causeenzymes to stop working due to hightemperatures.

Cohesion

Hydrogen bonds when in big numbersare strong which causes it to becohesive which means the moleculesstick to each other. Water will alsostick to other surfaces.

Capillary action allows water to moveagainst gravity which allows tops oftrees to be nourished. Surface tensionallows the water to be strong enoughto support insects as well as formdroplets on surfaces such as leaveswhich provide food sources for someorganisms.

Solvent Properties

Due to the fact that water is a polarmolecule it dissolves polar soluteseasily making water a good solvent.

Ionic solids dissociate in water whichmeans they break into their ions, themore soluble the solute, the easier itis to isolate the ions. It is also usefulfor metabolic reactions becausedissolved particles can diffuse andare likely to collide causing areactions. Water also is a goodtransport medium as it allows for the

nutrients that are dissolved to becarried through the circulatorysystem through diffusion orinterstitial fluid. Water is also denseallowing organisms to float or swim inwater.

(include uses as a coolant, medium for metabolic reactions, transport medium)

Stephen Taylor Bandung International Schoolhttp://sciencevideos.wordpress.com

H H

H H H H

O

O O

+ + + +

++

-

- -

The oxygen end is

slightly negative

The hydrogen end is

slightly positive

Hydrogen bones are the

attractions between

polar moleculesNot as strong as

covalent bonds but

attracts to opposite

charge

http://sciencevideos.wordpress.com/http://sciencevideos.wordpress.com/